This invention pertains to multi-packages for a plurality of containers, such as cans, which are held together by a carrier device. These devices are typically sheet-like with apertures formed creating a plurality of integrally connected bands which are particularly designed and dimensioned to by stretchingly applied around the top region of a can.
Various forms of carriers of the type referred to are shown in U.S. Pat. Nos. 2,874,835, 3,874,502, 4,018,331 and 4,219,117.
Such devices have become thinner and of less total material content through a variety of improvements in designs and have accordingly been designed to be stretched a significant amount in order to create a stable and integral package.
Carrier devices of the type described are typically manufactured by extruding sheet thermoplastic material, for example low density polyethylene, in thicknesses generally in the range of 0.012-0.030 inches. In typical plastic extruding operations, as the sheet is extruded, it is fed through a series of sizing and/or cooling rolls which are of a rather smooth finish consistent with conventional plastics manufacture.
The standard roll finish and resulting surface finish of the carrier is generally in the range of three to eight RMS (root mean square), which is a standard measurement unit for surface texture and an indication of how rough or smooth such a surface is. More recently, the instruments that are calibrated in RMS have given way to instruments that are calibrated for arithmetic average as a unit of height for roughness or as a unit for measuring surface finish. This RMS measurement and arithmetic average or roughness average is typically given in micro-inches. For example, a surface with a roughness average of 16, means that the surface has an arithmetical average absolute deviation from a means surface of 16 micro-inches (Mu in.).
A typical carrier device of the type described with a surface finish in the range of three to eight RMS, in conjunction with very high stretching forces, creates an extremely close fiting surface-to-surface contact between the carrier device and the can surface, especially when the surface finish of the can is in the same smooth surface finish range.
In certain instances this smooth finish/high stretch force creates a binding or adhering between the carrier and the can, particularly if sugar or any other sticky substance remains entrapped between the carrier device and the can.
In situations where a highly stretched carrier is adhered to a can, any attempt to rotate the can or to move the can relative to the carrier will create an excessive localized stress on the carrier and will likely break the carrier band or locally "neck-down" or stretch the band beyond its elastic limit.
It is accordingly an object of this invention to create a new and novel carrier which will permit relative rotation of a can within the carrier band without binding.
A further object of the invention is to create a carrier device and package which is manufactured with a surface texture sufficiently rough to prevent the deleterious close surface-to-surface contact between the carrier and the package.
The objects and advantages are found in the present invention which utilizes a surface finish in the range of at least 16-18 in roughness average, at least on the side of the carrier that contacts the container. This is to be contrasted with the standard, well-known and conventionally utilized surface finishes in the range of three to eight roughness average.
Other objects and features of the invention will be apparent upon perusal of the hereinafter following specification taken in conjunction with the drawings.